JPH0262018A - Capacitor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention provides a capacitor, more specifically, a safety function that utilizes fluctuations in the internal pressure of a sealed container housing the capacitor element to cut off current to the capacitor element. The present invention relates to a capacitor having a capacitor.

(Prior art) This type of capacitor uses the increased pressure to bulge and deform the top lid of the container when the internal pressure of the sealed container increases, and the capacitor element is connected to an external terminal provided on the top lid. When this safety function operates properly, explosions caused by dielectric breakdown of the capacitor element are prevented.

In conventional capacitors, the top lid is made of a thermoplastic resin plate with a predetermined thickness, and when the internal pressure of the sealed container rises abnormally, the top lid flexes into a bulge due to the flexibility of the thermoplastic resin itself. It is known that the deformable
045 Publication).

(Problem to be solved by the invention) By the way, in order to sensitively detect the increase in the internal pressure of a closed container and improve its operation accuracy, the top cover should be made of highly flexible thermoplastic resin as in the past. This is desirable.

In addition, in order to reliably disconnect the external terminal from the lead wire due to the bulging deformation of the top cover, the external terminal must be reliably pulled up by the top cover with a sufficiently large force when the bulge width of the top cover reaches a predetermined width. is required.

However, if the top cover is made of a simple thermoplastic resin plate with a predetermined thickness as in the past, the flexibility of the top cover is uniform in all parts including the area where the external terminals are installed, and the external terminals are connected to the lead wires. Therefore, due to the rise in internal pressure of the sealed container, the parts other than the part where the external terminal is installed bulge and deform at the initial stage, deforming the whole into a wavy shape, and the bulging and deforming part is pulled. In the next step, the external terminal mounting portion bulges and deforms, deforming into a dome shape as a whole, and the external terminal exhibits a behavior in which it is cut off from the lead wire. Furthermore, the manner in which the top lid deforms into a wavy shape is determined by the relationship between various factors, such as how the top lid is attached to the sealed container and how well the external terminals are installed. It is difficult to predict with certainty. Therefore, with conventional capacitors, it is difficult to accurately predict when the external terminal will be disconnected from the lead wire due to an abnormal increase in the internal pressure of the sealed container, and when the current flow to the capacitor element is cut off. There were constraints on increasing the accuracy of the operation.

This invention was made in view of the above circumstances, and although the pressure detection sensitivity can be maintained at the same level as before by devising the top cover, the operation when cutting off current to the capacitor element is difficult. It is an object of the present invention to provide a condenser whose accuracy can be easily improved.

(Means for Solving the Problems) In the capacitor of the present invention, the top cover is made of synthetic resin and is mounted under sealed pressure and provided with an external terminal connected to a lead wire led out from a capacitor element, and the top cover is made of synthetic resin. A linear flexible part that is softer than other parts is formed concentrically around the installation part to form an annular double inner and outer part, and the annular part sandwiched between the two flexible parts is the central part in the width direction. is the thickest, and the thickness gradually decreases as it approaches the inner flexible portion and the outer flexible portion, and the surface of this annular portion is formed in an upwardly expanding shape with an inner recess.

(Function) According to the capacitor having this configuration, an increase in the internal pressure of the sealed pressure is sensitively detected by the synthetic resin top cover. When the internal pressure rises abnormally, the top cover is pressed upward by the internal pressure, and the annular inner flexible part and outer flexible part of the top cover bend in opposite directions, and are surrounded by these flexible parts. The external terminal installation section that is currently in place will be pushed upwards. In this series of deformation processes, the annular part sandwiched between the inner and outer annular flexible parts and the external terminal installation part are less likely to deform than the flexible parts, and in particular, the annular part is thickest at the center in the width direction. Since the thickness of the meat gradually decreases as it approaches the inner flexible portion and the outer flexible portion, it hardly deforms, and therefore the upper lid bulges and deforms into a truncated conical shape as a whole. That is, although the upper lid is made of flexible synthetic resin, it bulges and deforms in a state similar to an elastic reversal movement due to an abnormal increase in internal pressure.

(Embodiment) Fig. 1 is a vertical cross-sectional view of a capacitor C according to an embodiment of the present invention. It is installed. The end of the lead wire 4.5 led out from the capacitor element 2 is held in the hole 7.8 of the support plate 6 arranged on the back side of the upper M3. External terminals 9.10 provided on the upper M3 are connected to the lead wires 4.5, respectively.

The top cover 3 is made of synthetic resin such as thermoplastic resin and has a circular shape, and the external terminals 9 and 10 are fitted into boss portions 11 and 12 provided in the center of the top cover 3 in left and right directions. There is. Further, as shown in detail in FIG. 4, a linear flexible portion 13, 14, which is softer than other portions, is formed concentrically around the external terminal installation portion , an annular portion Y surrounded by these flexible portions 13 and I4
As shown in FIG. 5 on an enlarged scale, the surface thereof is formed into a curved shape. Further, the annular portion Y is thickest at the center in the width direction, and the thickness gradually decreases as it approaches the inner flexible portion 13 and the outer flexible portion 14, and in the case of the embodiment, the cross-sectional shape of the annular portion Y is is in the shape of a crescent moon.

The inner flexible portion 13 described above can be easily formed by carving or molding a narrow groove 16 on the back side of the upper M3, and the outer flexible portion 14 can be formed by making the surface of the annular portion Y curved. It is formed by In addition, the inner flexible part 1
3 and the outer flexible portion 14 can be formed without changing the thickness of the top cover 3. For example, it is also possible to form only that part by using a resin layer that is more flexible than other parts. can.

The inner and outer annular flexible portions 13, 14 are preferably circular, but may also be polygonal with a large number of vertices, such as a dodecagon or a 24-gon. Further, various dimensions of the curved surface portion of the surface of the annular portion Y are appropriately set in consideration of the degree of increase in internal pressure of the closed container 1 shown in FIG. 1, etc. The operating accuracy when the upper lid 3 expands and deforms due to an increase in the internal pressure of the closed container 1 depends on the set position and number of flexible parts 13.14, the shape of the flexible parts 13.14, and the slope and width of the annular part Y. Dimensions, top M3
They should be appropriately selected in consideration of various factors such as the degree of increase in internal pressure, as they are related to the degree of flexibility of the synthetic resin constituting the material.

Figure 2 shows the normal state of the capacitor C, where the external terminal installation part X on the top cover 3 is recessed downward with respect to its surroundings, and the external terminals 9 and 10 are connected to the ends of the lead wires 4 and 5, respectively. has been done. When the internal pressure of the airtight container 1 rises abnormally, the pressure in the space between the support plate 6 and the top lid 3 also rises abnormally, and the top lid 3 is pushed upward by this pressure, and the top lid 3 is pushed inside as shown in Fig. 3. The flexible portion 13 and the outer flexible portion 14 are bent in opposite directions, and the external terminal installation portion X is pushed upward. In such a series of deformation processes, the annular portion Y and the external terminal installation portion In a state close to a reversal motion, the entire structure bulges and deforms into a truncated cone shape, and the external terminal 9.10 is momentarily cut off from the end of the lead wire 5.6, cutting off the current supply to the capacitor element 2. be done.

(Effects of the Invention) According to the present invention, when the internal pressure of the sealed container abnormally increases due to dielectric breakdown of a capacitor element, the top cover bulges and deforms due to the pressure, and the external terminal is disconnected from the lead wire. Since it reliably cuts off current to the capacitor element, it is possible to reliably prevent explosions and other accidents. Moreover, the bulging deformation of the upper lid is reliably performed in a state close to an elastic reversal motion whose behavior is determined by the flexibility of the annular flexible part, the setting position, the rigidity of the annular part, etc., and the wavy bulging Since deformation is less likely to occur, the timing at which the external terminal will be disconnected from the lead wire can be predicted with high accuracy, and its operation accuracy is improved.

In addition, since the surface of the annular part is formed in an upwardly expanding shape, the grooves used to form the flexible part on the surface of the top cover are no longer visible, resulting in a simpler appearance and an advantage of improving product value. .

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional view of a capacitor according to an embodiment of the present invention, Fig. 2 is a longitudinal cross-sectional view of the main part of the capacitor under normal conditions, and Fig. 3 is a longitudinal cross-sectional view of the main part of the capacitor when the top cover is bulging and deformed. , FIG. 4 is a sectional view of the upper cover, and FIG. 5 is an enlarged sectional view of a portion of FIG. 4. 1... Airtight container, 2... Capacitor element, 3...
Top lid, 4.5... Lead wire, 9.10... External terminal, 13.14... Flexible part, C... Capacitor,
X: External terminal installation part, Y: Annular part.

Claims (1)

[Claims] 1. A top lid that bulges and deforms when the internal pressure of the capacitor element increases is attached to the airtight container that houses the capacitor element, and an external terminal that connects to a lead wire led out from the capacitor element is provided on the top lid to prevent the bulge of the top lid. In capacitors whose external terminals are cut off from the lead wires due to deformation, the top cover is made of synthetic resin, and a linear flexible part that is softer than other parts is concentrically connected to the outside and outside around the external terminal installation part of the top cover. The annular part sandwiched between both flexible parts is thickest at the center in the width direction and gradually decreases in thickness as it approaches the inner flexible part and the outer flexible part. The capacitor is further characterized in that the surface of the annular portion is formed in an upwardly expanding shape with an inner recess.